The ability to form associative memories is one of the most important functions of an organism's nervous system. However, the molecular mechanisms underlying learning and associative memory formation have yet to be fully elucidated. Identifying molecules involved in these processes is important not only to gain an understanding of normal brain function, but can also lead to an understanding of disease states such as age-related cognitive decline and Alzheimer's disease. We will use the nematode Caenorhabditis elegans, which has a simple nervous system and its genes have conserved functions in higher organisms, to identify molecules that are most essential for learning and memory. We will identify these molecules combining two techniques developed in our lab, a novel long-term associative memory (LTAM) assay and RNA-seq of individual populations and compartments of neurons. In Aim 1, we will identify postsynaptic molecules that are involved in regulation of LTAM by labeling postsynapses with a translational RFP fusion of a scaffolding protein important for learning and memory, MAGI-1. After LTAM training, MAGI-1:RFP worms will be lysed and subjected to FACS in order to isolate fluorescent postsynaptic compartments. RNA will be purified from the neurons and subjected to RNA-seq. We will then determine the profile of postsynaptic genes induced by memory training. In Aim 2 we will characterize mRNAs identified in Aim 1. In Aim 2a we will use utilize RNAi and deletion strains to identify novel and conserved postsynaptic regulators of learning and memory. In Aim 2b, we will determine which mRNAs of interest may be locally translated by utilizing single molecule fluorescent in situ hybridization. Bioinformatic analysis of these RNAs will also reveal potential RNA binding proteins that regulate LTAM. In Aim 2c, we will determine if the protein products of mRNAs identified in Aims 2a and 2b are also synaptically localized. This will allow us to identify novel proteins that are located in the postsynaptic density and may regulate synaptic remodeling during learning and memory. In Aim 3, we will determine if aging causes defects in the postsynaptic processes involved in LTAM, including transcriptional reprogramming, local translation, and postsynaptic remodeling. We will accomplish this by repeating the experiments in Aim 1 and 2 in aged worms, to identify molecules that contribute to age-related cognitive decline.